The plant kingdom is the domain of biology. The general term for organisms that can produce the required organic matter through photosynthesis. In different biological boundary systems, the concept of plants and the groups they contain are different. For example, when organisms are divided into plants and animals, the plant kingdom includes algae, fungi, lichens, mosses, ferns and seed plants; In the five kingdoms system, the plant kingdom only includes multicellular photosynthetic autotrophic groups, and fungi, lichens, unicellular algae and prokaryotic cyanobacteria are not included. (Note: Some saprophytes, such as Gastrodia elata, orchids, etc. , belongs to heterotrophs, but still belongs to the plant kingdom.

The main difference between the plant kingdom and other biological groups is that it contains chlorophyll, can carry out photosynthesis and can make organic matter by itself; In addition, most of them live in a certain environment and cannot move freely (except a few lower algae), and their cells have cell walls; Cells are totipotent, that is, 1 plant cells can be cultured into 1 plants. The relationship between plants and human beings is extremely close, which is the basis for human beings and other creatures to survive.

Plants are more difficult to define accurately than we look. Although botanists describe a plant kingdom, it is much more difficult to define the boundary of the plant kingdom than the usual definition of "plant". We try to understand plants as multicellular eukaryotes, which have no sensory organs, move autonomously and consist of roots, stems and leaves (if intact). However, in biology, only vascular plants have "roots, stems and leaves". But to be fair, vascular plants are also plants that we contact every day. By 2005, there are about 400,000 known plants in the world.

Classification of plant kingdom

Flowerless plants; Moss gymnosperms

Flowering plants; angiosperm

The simplest classification of plant kingdom is divided into two categories according to the perfection of plant structure: lower plants and higher plants. Lower plants include algae (Chlorophyta, Euglenophyta, Chrysophyta, Xanthophyta, Dinophyta, Bacillariophyta, Cyanophyta, Phaeophyta, Rhodophyta), fungi (bacteria, myxomycetes, fungi) and lichens (lichens). Higher plants include bryophytes (Bryophyta), ferns (ferns) and seed plants (ferns).

A large number of plant species in nature are arranged according to a certain classification level, indicating the systematic position and attribution of each plant. Plants are divided into boundaries, phyla, class, order, family, genus and species, in which boundaries are the largest taxonomic unit, species are the basic taxonomic unit, similar species are combined into genera, similar genera are combined into families, and so on. In each rank unit, if there are many species, suborders, subfamilies, families, subfamilies, groups, subspecies, varieties, forms, etc. Through systematic classification, each plant can not only show its position in the plant kingdom, but also show its relationship with other plant species.